package demo.java.util;

import java.util.*;

public class CollectionDemo {

public static void main(String[] args) {

/* 固定长度列表 */

// List<Integer> oldList = Arrays.asList(1, 2, 3, 4, 5, 6);

/* 可变列表1 */

List<Integer> oldList = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5, 6));

oldList.add(null);

/* 可变列表2 */

List<Integer> newList = new ArrayList<>();

Collections.addAll(newList, 4, 5, 6, 7, 8, 9);

newList.add(null);

List<Collection<Integer>> result = compare(oldList, newList, true);

System.out.println("oldList=" + oldList + ", newList=" + newList);

System.out.println("result=" + result);

}

/**

* 比较新旧值返回差异部分：result[0]新增值，result[1]删除值，result[2]相同部分

*

* @param oldCollection 旧数据集

* @param newCollection 新数据集

* @param needSame 是否需要相同部分

* @return result[0]新增值，result[1]删除值，result[2]相同部分

*/

public static <T> List<Collection<T>> compare(final Collection<T> oldCollection, final Collection<T> newCollection, boolean needSame) {

List<Collection<T>> result = new ArrayList<>();

Collection<T> onlyInOld = new ArrayList<>(oldCollection);

Collection<T> onlyInNew = new ArrayList<>(newCollection);

onlyInOld.removeAll(newCollection);

onlyInNew.removeAll(oldCollection);

result.add(onlyInNew);

result.add(onlyInOld);

if (needSame) {

Collection<T> sameCollection = new ArrayList<>(oldCollection);

sameCollection.retainAll(newCollection);

result.add(sameCollection);

}

return result;

}

}